Bis (hydroxymethyl) cyclobutyl triazolopyrimidines

ABSTRACT

Antiviral activity is exhibited by compounds having the formula &lt;IMAGE&gt;  1  and its pharmaceutically acceptable salts wherein R1 is &lt;IMAGE&gt;   R6 is hydrogen, alkyl, substituted alkyl, or aryl; and R7 and R8 are independently hydrogen,   &lt;IMAGE&gt;

BRIEF DESCRIPTION OF THE INVENTION

This application is a divisional of U.S. Ser. No. 322,375 filed Mar. 13,1989, which is a continuation-in-part of application Ser. No. 175,376filed Mar. 30, 1988, now abandoned.

Antiviral activity is exhibited by compounds having the formula:##STR4## and its pharmaceutically acceptable salts. In formula I, andthroughout the specification, the symbols are as defined below. ##STR5##wherein R₂ is hydrogen, methyl, fluoro, chloro, bromo, iodo, hydroxy oramino; R₃ is fluoro, chloro, bromo, iodo, hydrogen; methyl,trifluoromethyl, ethyl, n-propyl, 2-fluoroethyl, 2-chloroethyl, or##STR6## wherein R₄ is chloro, bromo, iodo, hydrogen methyl ortrifluoromethyl; R₅ is alkyl; R₆ is hydrogen, alkyl, substituted alkyl,or aryl; and R₇ and R₈ are independently hydrogen, ##STR7##

Preferred compounds of formula 1 are when R₁ is ##STR8##

Most preferred compounds of formula 1 are when R₁ is ##STR9## The term"alkyl" refers to both straight and branched chain groups. Those groupshaving 1 to 10 carbons are preferred. The term "substituted alkyl"refers to alkyl groups having one or more substituents. Preferredsubstituents are halogen, amino, azido, hydroxy, cyano, trialkylammonium(wherein each alkyl group has 1 to 6 carbons), alkoxy of 1 to 6 carbons,aryl and carboxy. The term "aryl" refers to phenyl and phenylsubstituted with one, two or three substituents. Preferred substitutentsare alkyl of 1 to 6 carbons, alkoxy of 1 to 6 carbons, halogen,trifluoromethyl, amino, alkylamino, dialkylamino, nitro, cyano,alkanoyloxy of 2 to 11 carbons, carboxy, carbamoyl and hydroxy.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of formula 1, and the pharmaceutically acceptable saltsthereof, are antiviral agents that can be used to treat viral infectionin mammalian species such as domesticated animals (e.g., dogs, cats,horses and the like) and humans, and avian species (e.g., chickens andturkeys). The compounds of formula 1 wherein R₁ is ##STR10## areeffective against one or more of the following viruses: herpes simplexvirus 1 and 2, varicellazoster viruses, cytomegalovirus, vaccinia virus,murine leukemia virus and human immunodeficiency virus (HIV). They arealso believed to be active against a variety of other DNA andretroviruses. Exemplary DNA viruses in addition to those named aboveinclude other herpes viruses (e.g., Epstein-Barr virus, pseudorabiesvirus, and the like), other poxviruses (e.g. monkey pox and myoma),papovaviruses (e.g., the papilloma viruses), hepatitis B virus, andadenoviruses. Exemplary retroviruses in addition to those named aboveinclude those effecting man, such as human T-cell lymphotropic viruses(HTLV), and those effecting other animals, such as feline leukemia virusand equine infectious anemia virus. All of the other compounds offormula 1 with the exception of those wherein R₁ is ##STR11## arebelieved to be active against one or more of the following viruses:herpes simplex virus 1 and 2, varicella-zoster virus, cytomegalovirus,and the retroviruses and other DNA viruses described above. Thecompounds of formula 1 wherein R₁ is ##STR12## are believed to be activeagainst the various DNA and retroviruses described above with theexception of herpes simplex virus 1 and 2, varicella-zoster virus andcytomegalovirus.

The compounds of this invention may be administered parenterally (forexample, by intravenous, intraperitoneal or intramuscular injection),orally or topically depending on whether the preparation is used totreat internal or external viral infections.

For internal infections, the compounds may be administered orally orparenterally in an amount effective to treat the infection. The dosagewill, of course, depend on the severity of the infection, but willlikely be in the range of about 1.0 to 50 mg/kg of body weight. Thedesired dose may be administered several times daily at appropriateintervals.

For infections of the eye, or other external tissues, e.g. mouth andskin, the compositions may be applied to the infected part of the bodyof the patient topically as an ointment, cream, aerosol, gel, powder,lotion, suspension or solution (e.g. as in eye drops). The concentrationof the compound in the vehicle will, of course, depend on the severityof the infection, but will likely be in the range of about 0.1 to 7% byweight.

A compound of formula 1 wherein R₁ is ##STR13## and R₇ and R₈ arehydrogen can be prepared from an intermediate of formula ##STR14##wherein P is a protecting group such as acyl, benzyl or silyl, and X isa leaving group such as chloro, bromo, iodo or an aryl or alkylsulfonate well known in the art (e.g., p-toluenesulfonyloxy ormethanesulfonyloxy). The term "acyl" refers to ##STR15## wherein R₉ is alower alkyl group of 1-6 branched or straight chain carbon atoms or aphenyl group. The term "silyl" refers to silyl protecting groups wellknown in the art [e.g., t-butyldimethylsilyl, t-butyldiphenylsilyl,(triphenylmethyl)dimethylsilyl, methyldiisopropylsilyl, ortriisopropylsilyl].

Reaction of a compound of formula 2 with a protected form of guaninesuch as a compound of formula ##STR16## in the presence of a base suchas potassium carbonate, sodium hydride, or potassium hydride in anaprotic polar solvent such as dimethylformamide, dimethyl sulfoxide, orsulfolane (tetramethylene sulfone) yields the corresponding compound offormula ##STR17##

Optionally, the reaction can be run in the presence of a metal chelatingcatalyst such as 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane). Removal of theprotecting groups from a compound of formula 4 yields a compound offormula 1 wherein R₁ is ##STR18## and R₇ and R₈ are hydrogen.

When the protecting group P in 4 is an acyl group, the protecting groupP can be selectively removed using, for example, catalytic sodiummethoxide in methanol or methanolic ammonia. Subsequent removal of theO-benzyl protecting group on the purine moiety can be accomplished bytreatment with aqueous alcoholic mineral acid (e.g., aqueous methanolichydrochloric acid), sodium in liquid ammonia, or by hydrogenolysis(e.g., palladium hydroxide on carbon in cyclohexene and ethanol).Alternatively, the purine O-benzyl protecting group can be removedinitially, followed by removal of the acyl protecting groups.

When the group P in compound 4 is a silyl protecting group, removal ofthe P group can be accomplished using fluoride ion (e.g.,tetrabutylammonium fluoride in tetrahydrofuran). The purine O-benzylprotecting group can then be removed with aqueous alcoholic mineral acidor by hydrogenolysis. When the protecting group P in 4 is benzyl,removal of all the benzyl protecting groups can be effected using eithersodium in liquid ammonia or hydrogenolysis (e.g. palladium hydroxide oncarbon in cyclohexene and ethanol). Alternatively, all of the benzylprotecting groups can be removed by treatment with boron trichloride indichloromethane.

Reaction of a compound of formula 2 with compound ##STR19## underconditions analogous to those used in the preparation of compound 4provides a compound of formula ##STR20##

Selective removal of the protecting group P provides a compound offormula 1 wherein R₁ is ##STR21## and R₇ and R₈ are hydrogen. Forexample, when the protecting group P in 6 is acyl, the P group can beselectively removed using, for example, catalytic sodium methoxide inmethanol. When the protecting group P in 6 is silyl, the protectinggroup can be selectively removed by treatment with fluoride ion (e.g.,tetrabutylammonium fluoride). When the protecting group P in 6 isbenzyl, removal of the P group can be selectively performed by treatmentwith boron trichloride.

Acid hydrolysis (e.g., using hot aqueous hydrochloric acid) of thechloro group of a compound of formula 1 wherein R₁ is ##STR22## and R₇and R₈ are hydrogen provides a compound of formula 1 wherein R₁ is##STR23## and R₇ and R₈ are hydrogen.

A compound of formula 2 can be prepared as follows: Reaction of diethylfumarate and ketene diethyl acetal in hot t-butanol, yields a compoundof formula 7 as a racemic mixture (see K. C. Brannock, et al., J. Org.Chem., 29, 940 (1964)). Treatment of a compound of formula 7 with areducing agent such as lithium aluminum hydride in a solvent such asdiethyl ether or tetrahydrofuran yields diol 8. The hydroxyl groups canbe protected with a protecting group "P" by methods known in the art,yielding a compound of formula 9. Deketalization of 9 using, forexample, p-toluenesulfonic acid in acetone or aqueous sulfuric acid inacetonitrile, provides a compound of formula 10, which on treatment witha reducing agent (e.g. sodium borohydride or sodium cyanoborohydride inan alcohol such as methanol, ethanol, or isopropanol) affords a compoundof formula 11 as the minor product, along with an isomeric compound offormula 12 as the major product, which can be separated bychromatography. Alternatively, a compound of formula 10 can be treatedinitially with lithium tri-sec-butylborohydride or lithiumtrisiamylborohydride in tetrahydrofuran, and then with aqueous hydrogenperoxide and sodium bicarbonate to give a compound of formula 11 as themajor product and a compound of formula 12 (if present) as the minorproduct, which can be separated (if necessary) by chromatography. Thecompound of formula 11 can be converted to a compound of formula 2 bymethods known in the art. For example, treatment of 11 withp-toluenesulfonyl chloride or methanesulfonyl chloride in pyridineyields a compound of formula 2 wherein X is p-toluenesulfonyloxy ormethanesulfonyloxy, respectively. The compound of formula 2 wherein X isp-toluenesulfonyloxy or methanesulfonyloxy can also be prepared from theisomeric compound of formula 12 by treatment with p-toluenesulfonic acidor methanesulfonic acid, respectively, in the presence of triethylamine,triphenylphosphine, and diethyl or diisopropyl azodicarboxylate in asolvent such as toluene, ether or dioxane.

Alternatively, treatment of the compound of formula 12 with amethyltriphenoxyphosphonium halide or methyltriphenylphosphonium halide(i.e. chloride, bromide or iodide) in a solvent such asdimethylformamide provides a compound of formula 2 wherein X is chloro,bromo, or iodo. In yet another alternative, a compound of formula 2wherein X is chloro, bromo, or iodo can be prepared from the compound offormula 12 using triphenylphosphine, diethyl (or diisopropyl)azodicarboxylate, and a source of halide such as methyl iodide, methylbromide, or dichloromethane according to methodology known in the art.See for example, H. Loibner, et al., Helv. Chim. Acta., 59, 2100 (1976).

The above description is shown in the following schematic: ##STR24##

A compound of formula 1 wherein R₁ is ##STR25## and R₇ and R₈ arehydrogen can be prepared from a compound of formula 6. For example, whenthe P group in 6 is an acyl or silyl protecting group, the chloro groupcan first be reduced by hydrogenation (e.g. ammonium formate andpalladium on carbon in methanol or ethanol, palladium on carbon incyclohexene and ethanol, or palladium on carbon, hydrogen and ethanol)and then the protecting groups P can be removed using either catalyticsodium methoxide in methanol or methanolic ammonia when P is acyl, andfluoride ion when P is silyl. Alternatively, the acyl or silylprotecting groups P can be removed first and then the chloro group canbe reduced. When the protecting group P in 6 is benzyl, deprotection andreduction of the chloro group can be accomplished simultaneously byhydrogenolysis (e.g., palladium hydroxide on carbon in cyclohexene andethanol; or ammonium formate or formic acid and palladium on carbon inmethanol or ethanol).

Alternatively, this compound of formula 1 can be prepared by reacting anoptionally protected compound of formula ##STR26## with a compound offormula 2 according to procedures analogous to those used in thepreparation of a compound of formula 4, followed by removal of theprotecting groups by methods known in the art. An optionally protectedform of compound 13 can be protected at the amino (--NH₂) group by suchexemplary groups as acyl, trityl, or substituted trityl. Exemplarysubstituted trityl groups are 4-monomethoxytrityl and4,4'-dimethoxytrityl.

A compound of formula 1 wherein R₁ is ##STR27## and R₇ and R₈ arehydrogen can be prepared from a compound of formula 6 by treatment withhot methanolic ammonia according to methods known in the art (e.g., J.C. Martin, et al., J. Med. Chem. 28, 358(1985)). When the protectinggroup P in 6 is acyl, for example, treatment with hot methanolic ammoniaresults in substitution of the chloro group by an amino group andsimultaneous removal of the acyl protecting groups. When the protectinggroup P is a benzyl or silyl group, replacement of the chloro group byan amino group can be accomplished first, and then the protecting groupsP can be removed (for example, by hydrogenolysis or treatment with borontrichloride in the case where P is benzyl, or by treatment with fluorideion in the case where P is a silyl group).

Alternatively, this compound of formula 1 can be prepared by reacting anoptionally protected compound of formula ##STR28## with a compound offormula 2 according to procedures analogous to those used in thepreparation of a compound of formula 4, followed by removal of theprotecting groups by methods known in the art. An optionally protectedform of 14 can be protected at the amino (--NH₂) group by such exemplarygroups as acyl, trityl or substituted trityl.

A compound of formula 1 wherein R₁ is ##STR29## and R₇ and R₈ arehydrogen can be prepared from a compound of formula 6 or from a compoundof formula 1 wherein R₁ is ##STR30## and R₇ and R₈ are hydrogen bymethods known in the art. See, for example, J. F. Gerster, et al., J.Amer. Chem. Soc., 87, 3752 (1965); K. K. Ogilvie, et al., Can. J..Chem., 62, 2702 (1984); M. R. Harnden, et al., J. Med. Chem., 30, 1636(1987).

Alternatively, the compound of formula 1 can be prepared by reacting acompound of formula ##STR31## with a compound of formula 2 according toprocedures analogous to those used in the preparation of a compound offormula 4, followed by removal of the protecting groups P by methodsknown in the art. The compound of formula 15 can be prepared from thecompound of formula 5 by methods known in the art. See, for example, W.A. Bowles, et al., J. Med. Chem., 6, 471 (1963); M. MacCoss, et al.,Tetrahedron Lett., 26, 1815 (1985).

Reaction of a compound of formula 2 with an optionally protected form ofa compound of formula ##STR32## in the presence of a base such aspotassium carbonate, sodium hydride, or potassium hydride in a polaraprotic solvent (e.g., dimethylformamide, dimethyl sulfoxide orsulfolane), in the optional presence of 18-crown-6 or 15-crown-5, gives,after removal of the protecting groups, the corresponding compound offormula 1 wherein R₁ is ##STR33## and R₇ and R₈ are hydrogen. Theoptionally protected forms of compound 16 can be protected at the amino(--NH₂) group by such exemplary groups as acyl, trityl, or substitutedtrityl.

Alternatively, reaction of a compound of formula 2 with a compound offormula ##STR34## according to procedures analogous to those used in thepreparation of a compound of formula 4, followed by removal of theprotecting groups, provides the compound of formula 1 wherein R₁ is##STR35## and R₇ and R₈ are hydrogen.

Alternatively, this compound of formula 1 can be prepared by reaction of2 with a compound of the formula ##STR36## by procedures analogous tothose used in the preparation of 4, followed by acid hydrolysis of thechloro group and simultaneous or subsequent removal of protecting groupsP.

Reaction of the compound of formula 2 with a compound of formula##STR37## by methodology analogous to that used to prepare a compound offormula 4, and subsequent removal of the P protecting groups, yields thecorresponding compound of formula 1 wherein R₁ is ##STR38## and R₇ andR₈ are hydrogen.

Alternatively, this compound of formula 1 can be prepared by reaction ofa compound of formula ##STR39## with a compound of formula 2 by methodsanalogous to those used in the preparation of a compound of formula 4.This affords the corresponding compound of formula ##STR40## Treatmentof a compound of formula 20 with hot ammonia in an alcohol (such as,methanol or ethanol) and simultaneous or subsequent deprotection of theP protecting groups yields the corresponding compound of formula 1wherein R₁ is ##STR41## and R₇ and R₈ are hydrogen.

The compound of formula 1 wherein R₁ is ##STR42## and R₇ and R₈ arehydrogen can be prepared from a compound of formula 20 by selectiveremoval of the P protecting groups. For example, when the protectinggroup P in 20 is acyl, the P group can be selectively removed using, forexample, catalytic sodium methoxide in methanol. When the protectinggroup P in 20 is silyl, the protecting group P can be selectivelyremoved by treatment with fluoride ion (e.g., tetrabutylammoniumfluoride). When the protecting group P in 20 is benzyl, removal of the Pgroup can be selectively performed by treatment with boron trichloride.

Acid hydrolysis (e.g., using hot aqueous hydrochloric acid) or basichydrolysis (e.g., aqueous methanolic sodium hydroxide) of the chlorogroup of a compound of formula 1 wherein R₁ is ##STR43## and R₇ and R₈are hydrogen provides a compound of formula 1 wherein R₁ is ##STR44##and R₇ and R₈ are hydrogen. Alternatively, this compound of formula 1can be prepared by treatment of a compound of formula 1 wherein R₁ is##STR45## and R₇ and R₈ are hydrogen with adenosine deaminase accordingto methods known in the art (e.g., M. J. Robins, et al., J. Med. Chem.,27, 1486 (1984); K. K. Ogilvie, et al., Can. J. Chem., 62, 241 (1984)).

Compounds of formula 1 wherein R₁ is ##STR46## and R₂ is methyl, chloro,bromo, iodo, hydroxy, or amino, and R₇ and R₈ are hydrogen, can beprepared from the corresponding compound of formula 1 wherein R₂, R₇ andR₈ are hydrogen by methods known in the art.

The compound of formula 1 wherein R₁ is ##STR47## and R₂ is fluoro, andR₇ and R₈ are hydrogen, can be prepared from the corresponding compoundof formula 1, wherein R₂ is bromo or iodo, and R₇ and R₈ are hydrogen.The amino (--NH₂) and/or hydroxyl groups can be optionally protectedwith acyl groups. Treatment with fluoride ion (e.g., sodium or potassiumfluoride in a solvent such as dimethylformamide or diethylene glycol, ortetrabutylammonium fluoride in tetrahydrofuran) followed by removal (ifnecessary) of the optional acyl protecting groups using, for example,catalytic sodium methoxide in methanol or methanolic ammonia providesthe compound of formula 1 wherein R₁ is ##STR48## and R₇ and R₈ arehydrogen.

Compounds of formula 1 wherein R₁ is ##STR49## and R₂ is methyl, chloro,bromo, iodo, hydroxy, or amino, and R₇ and R₈ are hydrogen, can beprepared from the corresponding compound of formula 1 wherein R₂, R₇ andR₈ are hydrogen using procedures known in the art. The amino (--NH₂)and/or hydroxyl groups can be optionally protected by acyl groups.

The compound of formula 1 wherein R₁ is ##STR50## and R₂ is fluoro, andR₇ and R₈ are hydrogen, can be prepared from the corresponding compoundof formula 1 wherein R₂ is bromo or iodo, and R₇ and R₈ are hydrogen.The amino (--NH₂) and/or hydroxyl groups can be optionally protectedwith acyl groups. Treatment with fluoride ion (e.g., sodium or potassiumfluoride in a solvent such as dimethylformamide or diethylene glycol, ortetrabutylammonium fluoride in tetrahydrofuran) followed by removal (ifnecessary) of the optional acyl protecting groups, using, for example,catalytic sodium methoxide in methanol or methanolic ammonia, providesthe compound of formula 1 wherein R₁ is ##STR51## and R₇ and R₈ arehydrogen.

Compounds of formula 1 wherein R₁ is ##STR52## and R₂ is methyl, chloro,bromo, iodo, hydroxy, or amino and R₇ and R₈ are hydrogen, can beprepared from the corresponding compound of formula 1 wherein R₂, R₇ andR₈ are hydrogen following procedures known in the art. The amino (--NH₂)and/or hydroxyl groups can be optionally protected by acyl groups.

The compound of formula 1 wherein R₁ is ##STR53## and R₇ and R₈ arehydrogen can be prepared from a compound of formula ##STR54## (wherein Pis an acyl protecting group) by methodology known in the art. Thecompound of formula 21 can be prepared by known methods from thecompound of the formula 1 wherein R₁ is ##STR55## and R₇ and R₈ arehydrogen. The hydroxyl groups can be optionally protected by acylgroups.

For general methods of preparing 8-substituted purine nucleosides andnucleoside analogs see, for example: M. J. Robins, et al., J. Med.Chem., 27, 1486 (1984); R. E. Holmes, et al., J. Amer.. Chem. Soc., 86,1242 (1964); R. A. Long, et al.. J. Org. Chem., 32, 2751 (1967); R. E.Holmes, et al., J. Amer. Chem. Soc., 87. 1772 (1965); M. Ikehara, etal., Tetrahedron, 26, 4251 (1970); H. J. Brentnall, et al., TetrahedronLett. 2595 (1972); M. Ikehara, et al., Chem. Pharm. Bull., 13, 1140(1965); M. Ikehara, et al., Chem. Commun., 1509 (1968).

The compound of formula 1 wherein R₁ is ##STR56## and R₇ and R₈ arehydrogen can be prepared from the compound of formula 1 wherein R₁ is##STR57## and R₇ and R₈ are hydrogen by following known procedures. See,for example, J. A. Montgomery et al., in "Synthetic Procedures inNucleic Acid Chemistry", Vol. 1, W. W. Zorbach and R. S. Tipson, Eds.,Interscience Publishers (John Wiley and Sons), N.Y., p. 205, 1968.

The compound of formula ##STR58## wherein R₃ is hydrogen, fluoro,methyl, ethyl, n-propyl, 2-chloroethyl, or 2-fluoroethyl can be preparedby reaction of the corresponding compound of formula ##STR59## with acompound of formula 2 in the presence of a base such as potassiumcarbonate, sodium hydride, or potassium hydride, in an aprotic polarsolvent (e.g., dimethylformamide, dimethylsulfoxide, or sulfolane), inthe optional presence of 18-crown-6 or 15-crown-5, to yield anintermediate of formula ##STR60## Removal of the protecting groups Pprovides the corresponding compound of formula 22. For example, when Pis acyl, the protecting groups can be removed by treatment with sodiummethoxide in methanol or methanolic ammonia, or when P is a silyl group,deprotection can be accomplished with fluoride ion. When P is a benzylgroup, deprotection can be accomplished by hydrogenolysis (e.g.,palladium hydroxide on carbon in cyclohexene and ethanol) or bytreatment with boron trichloride.

The compound of formula 23 wherein R₃ is 2-chloroethyl or 2-fluoroethylcan be prepared by methods known in the art [H. Griengl, et al., J. Med.Chem., 30, 1199 (1987); J. Med. Chem., 28, 1679 (1985)].

The compound of formula 22 wherein R₃ is fluoro can also be preparedfrom the corresponding compound 22 wherein R₃ is hydrogen and thehydroxy groups are optionally protected with a group such as acyl byfluorination with trifluoromethyl hypofluorite using methodology knownin the art. For example, see M. J. Robins, et al., J. Amer. Chem. Soc.,93, 5277 (1971) and Chem. Communs., 18 (1972); T. S. Lin, et al., J.,Med. Chem., 26, 1691 (1983).

The compounds of formula 22 wherein R₃ is 2-chloroethyl and2-fluoroethyl can also be prepared from a compound of formula ##STR61##wherein P₂ and P are different protecting groups wherein P₂ can beselectively removed in the presence of P. For example, when P₂ is asilyl, trityl or substituted trityl group, P can be a benzyl or acylgroup. Similarly, when P₂ is an acyl or benzyl group, P can be a silylprotecting group. Selective removal of the protecting group P₂ yields acompound of formula 24 wherein R₃ is 2-hydroxyethyl. Treatment of thiscompound with triphenylphosphine-carbon tetrachloride and subsequentremoval of protecting groups P affords the compound of formula 22wherein R₃ is 2-chloroethyl. Similar treatment usingtriphenylphosphine-N-bromosuccinimide or triphenylphosphineN-bromosuccinimide-tetrabutylammonium iodide in place oftriphenylphosphine-carbon tetrachloride (e.g., see H. Griengl, et al.,J. Med. Chem., 28, 1679 (1985)) affords compounds of formula 24 whereinR₃ is 2-bromoethyl or 2-iodoethyl, respectively. Subsequent treatmentwith fluoride ion, followed by removal of protecting groups P, providesthe compound of formula 22 wherein R₃ is 2-fluoroethyl. When P is asilyl group, deprotection will occur upon treatment with fluoride ion.Alternatively, treatment of a compound of formula 24, wherein R₃ is2-hydroxyethyl, with diethylaminosulfur trifluoride provides, uponremoval of the protecting groups P, a compound of formula 22 wherein R₃is 2-fluoroethyl.

The compound of formula 25 can be prepared by reaction of a compound offormula ##STR62## with a compound of formula 2 by methods analogous tothose used for the preparation of 24 wherein, for example, R₃ ishydrogen, methyl or ethyl. The compound of formula 26 can be preparedfrom the corresponding free alcohol by methods known in the art.

The compound of formula ##STR63## wherein R₃ is hydrogen, fluoro,methyl, ethyl, n-propyl, 2-chloroethyl, or 2-fluoroethyl can be preparedfrom the corresponding compound of formula 24 (wherein P, for example,is an acyl protecting group) by methods known in the art. See, forexample, I. Wempner, et al., in "Synthetic Procedures in Nucleic AcidChemistry", Vol. 1, W. W. Zorbach and R. S. Tipson, Eds., IntersciencePublishers, N.Y., p. 299, 1968; T. S. Lin, et al., J. Med. Chem., 26,1691 (1983); P. Herdewijn, et al., J. Med. Chem., 28, 550 (1985).Deprotection using methanolic ammonia or sodium methoxide in methanolyields the corresponding compound of formula 27.

Alternatively, the compound of formula 27, wherein R₃ is fluoro,hydrogen, methyl, ethyl, n-propyl, 2-chloroethyl, or 2-fluoroethyl, canbe prepared by reaction of the corresponding compound of formula##STR64## with a compound of formula 2 in the presence of a base such aspotassium carbonate, sodium hydride, or potassium hydride in an aproticsolvent (e.g. dimethylformamide, dimethyl sulfoxide, or sulfolane), inthe optional presence of 18-crown-6 or 15-crown-5, and subsequentremoval of the protecting groups. Optionally, the amino (--NH₂) group in28 can be protected, e.g., with an acyl group. Removal of thisprotecting group can be accomplished using sodium methoxide in methanolor methanolic ammonia.

Alternatively, the compound of formula 27 wherein R₃ is fluoro can beprepared from the corresponding compound wherein R₃ is hydrogen byfluorination with trifluoromethyl hypofluorite using methodology knownin the art. Fluorination can also be performed on the compounds offormula 27 wherein R₃ is hydrogen and the hydroxyl and/or amino groupsare protected, for example, by an acyl. After fluorination, deprotectionusing methanolic ammonia or aqueous hydroxide affords the compound offormula 27 wherein R₃ is fluoro. See, for example, M. J. Robins, et al.,J. Amer. Chem. Soc., 93, 5277 (1971) and Chem. Commun., 18 (1972); T. S.Lin, et al., J. Med. Chem., 26, 1691 (1983).

The compounds of formula 22 and 27 wherein R₃ is chloro, bromo, or iodocan be prepared from the corresponding compounds of formula 22 and 27wherein R₃ is hydrogen by methods known in the art. See, for example,"Basic Principals in Nucleic Acid Chemistry", Vol. 1, P.O.P. Ts'O, Ed.,Academic Press, N.Y., p. 146, 1974; P. K. Chang in "Nucleic AcidChemistry" Part 3, L. B. Townsend and R. S. Tipson, Eds., John Wiley andSons, N.Y., p. 46, 1986.

The compounds of formula 22 and 27 wherein R₃ is trifluoromethyl can beprepared from the corresponding compounds of formula 22 and 27 whereinR₃ is iodo and the hydroxy and amino (--NH₂) groups are protected, forexample, by an acyl, by treatment with trifluoromethyl iodide and copperaccording to procedures known in the art. Subsequent deprotection usingmethanolic ammonia or sodium methoxide in methanol yields thecorresponding compound of formulas 22 and 27 wherein R₃ istrifluoromethyl. See, for example, Y. Kobayashi, et al., J. Chem. Soc.Perkin 1, 2755 (1980); S. Lin. et al., J. Med. Chem., 26, 1691 (1983).

The compounds of formula 22 and 27 wherein R₃ is ##STR65## and R₄ ischloro, bromo, iodo, hydrogen, methyl or trifluoromethyl can be preparedfrom the corresponding compounds of formula 22 and 27 wherein R₃ is iodoor --HgCl via organopalladium intermediates. The compounds of formula 22and 27 wherein R₃ is --HgCl can be prepared from the correspondingcompounds of formula 22 and 27 wherein R₃ is hydrogen by methods knownin the art. See, for example, references in E. DeClercq, et al.,Pharmac. Ther., 26, 1 (1984); M. E. Perlman, et al., J. Med. Chem., 28,741 (1985); P. Herdewijn, et al., J. Med. Chem., 28, 550 (1985); D. E.Bergstrom, et al., J. Med. Chem., 27, 279 (1984).

Compounds of formula 1 wherein R₁ is ##STR66## can be prepared from thecorresponding compounds of formula 1 wherein R₁ is ##STR67## by methodsknown in the art.

Compounds of formula 1 wherein one or both R₇ and R₈ are ##STR68## canbe prepared by methods known in the art from the corresponding compoundsof formula 1 wherein R₇ and R₈ are hydrogen.

For examples of acylation procedures see: "Synthetic Procedures inNucleic Acid Chemistry", Vol. 1, W. W. Zorbach and R. S. Tipson, Eds.,John Wiley and Sons, 1968; "Nucleic Acid Chemistry," Part 1, L. B.Townsend and R. S. Tipson, Eds., John Wiley and Sons, 1978; Y. Ishido,et al., Nucleosides and Nucleotides, 5, 159 (1986); J. C. Martin, etal., J. Pharm. Sci., 76, 180 (1987); A. Matsuda, et al., Synthesis, 385(1986).

Compounds of formula 1 wherein R₁ is ##STR69## can be prepared from thecorresponding compound of formula 1 wherein R₁ is ##STR70## byprocedures known in the art. See, for example, A. Holy and J. Zemlicka,Collect. Czech. Chem. Commun., 32, 3159 (1967); K.K. Ogilvie, et al.,Nucleosides and Nucletides, 4, 507 (1985); M. H. Caruthers, et al., J.Amer. Chem. Soc., 108, 2040 (1986).

Compounds of the formula 1 wherein R₇ and/or R₈ are --PO₃ H₃ can beprepared from the corresponding compounds of formula 1 wherein R₇ and R₈are hydrogen by procedures known in the art. See, for example, H.Schaller, et al., J. Amer. Chem. Soc , 85, 3821 (1963); J. Beres, etal., J. Med. Chem., 29, 494 (1986); R. Noyori, et al., Tet, Lett., 28,2259 (1987); W. Pfeiderer, et al., Helv. Chim. Acta., 70, 1286 (1987);"Nucleic Acid Chemistry". Part 2, L. B. Townsend and R. S. Tipson, Eds.,John Wiley and Sons, 1978.

The stereochemistry shown for the compounds of this invention andintermediates leading to compounds of this invention is relative, notabsolute. It is drawn to show that in the compounds of this invention,the base represented by R₁ is trans to the vicinal --CH₂ OH substituent,and the --CH₂ OH substituents are trans to each other.

The compounds of formula 1 wherein R₁ is ##STR71## can form acidaddition salts with inorganic or organic acids, Illustrative are thehydrohalide (e.g., hydrochloride and hydrobromide), alkylsulfonate,sulfate, phosphate and carboxylate salts.

The compounds of formula I wherein R₁ is ##STR72## can form basic saltswith inorganic and organic bases. Illustrative are alkali metal salts(e.g., sodium and potassium), alkaline earth metal salts (e.g. calciumand magnesium), ammonium and substituted ammonium salts.

The compounds of formula 1 wherein R₇ and/or R₈ are --PO₃ H₂ can formbasic salts with inorganic and organic bases. Illustrative are thealkali metal salts (e.g., sodium and potassium), alkaline earth metalsalts (e.g., calcium and magnesium), ammonium and substituted ammoniumsalts.

The following examples are specific embodiments of this invention.

EXAMPLE 1 (1α,2β,3α)-9-[2,3-Bis(hydroxymethyl) cyclobutyl]guanine (A).Ketene Diethyl Acetal

This was prepared using the method described in "Organic Syntheses",Coll. Vol. III, E. C. Horning, Ed., John Wiley and Sons, N.Y. p 506(1955). To a solution of potassium tert-butoxide (28.5 g, 0.254 mol) indry tert-butanol (150 ml., dried over 3 Å molecular sieves) at 50° wasadded bromoacetaldehyde diethyl acetal (38.5 ml, 0.254 mol). A columnfilled with glass helices (20×1.4 cm) with a total reflux partialtake-off still head was placed on top of the reaction flask. Thetemperature of the oil bath was slowly raised to 100° C. After thereaction had refluxed for 35 minutes, the tert-butanol was distilled offover ca. 16 hours at a rate of 4.5 drops/min with a reflux ratio at thestill head of 22:4.5. The oil bath was cooled to 20° and thehelices-filled column was replaced by a short path distillationapparatus. Distillation at 20-50° and ca. 4 mm gave 26.96 g of a mixturecontaining 23.31 g of ketene diethyl acetal and 3.66 g of tert-butanolas determined by, ¹ H-NMR integration.

(B). (trans)-3,3-Diethoxy-1,2-cyclobutanedicarboxylic acid, diethylester

This was prepared by modification of the method of K. C. Brannock, etal., J Org. Chem., 29, 840 (1964). To a solution of 25.27g of the abovemixture containing 21.63 g (0.186 mol) of ketene diethyl acetal in drytert-butanol (60 ml) was added diethyl fumarate (28.28 ml, 0.173 mol).This was heated at 82° for 7 days. The reaction was concentrated invacuo , and the residue was divided into portions of 3 g (A) and 39 g(B). Portion A was chromatographed on Merck silica gel-60 (1.5×30 cm) in19:1 hexane:ethyl acetate. Fractions containing product were combinedand concentrated to give 567 mg. Portion B was chromatographed twice onMerck silica gel-60 (35×5 cm) in the same solvent. Fractions containingproduct were combined and concentrated to give 10.43 g. The total yieldof desired product was 10.99 g.

(C). (trans)-3,3-Diethoxy-1,2-cyclobutanedimethanol

To a suspension of lithium aluminum hydride (2.38 g, 0.0627 mol) in dryTHF (50 ml) was added slowly(trans)-3,3-diethoxy-1,2-cyclobutanedicarboxylic acid, diethyl ester(11.29 g, 0.0392 mol) in THF (25 ml) so that a gentle reflux wasmaintained. The reaction was heated at 55° for 4 hours and then dilutedwith ether (100 ml) and poured into saturated aqueous ammonium chloride(100 ml). The pH was lowered to 4 with 3M sulfuric acid. The suspensionwas extracted with ether (4×100 ml) and then chloroform (3×100 ml). Theether extracts were combined, dried over sodium sulfate, filtered andconcentrated to give 5.613 g of desired product. The chloroform extractswere combined, dried over sodium sulfate, filtered and concentrated togive 112 mg of additional desired product.

(D). (trans)-3,3-Diethoxy-1,2-cyclobutanedimethanol, dibenzoate ester

To a solution of (trans)-3,3-diethoxy-1, 2-cyclobutanedimethanol (5.7 g,0.028 mol) in dry pyridine (40 ml) under nitrogen at 0° was added, over5 minutes, benzoyl chloride (9.73 ml. 0.0838 mol). This was warmed toroom temperature and a precipitate formed. After 2 hours, water (20 ml)was added, and the reaction was stirred overnight. The solvents wereremoved in vacuo. The residue was dissolved in ethyl acetate (400 ml)and washed with water (2×150 ml), 1N hydrochloric acid (2×150 ml), andsaturated sodium bicarbonate (3×150 ml). The organic layer was driedover sodium sulfate, filtered and concentrated to give 10.97 g ofdesired product.

(E) (trans)-2,3-Bis[(benzoyloxy)methyl]cyclobutanone

To a solution of (trans)-3,3-diethoxy-1,2-cyclobutanedimethanol,dibenzoate ester (10.87 g, 0.0263 mol) in acetone (200 ml) was addedp-toluenesulfonic acid (250 mg, 0.00132 mol). The reaction was refluxedfor 3 hours. The solution was concentrated in vacuo. The residue wasdissolved in ethyl acetate (200 ml) and washed with saturated sodiumbicarbonate (2×200 ml). The aqueous layer was back extracted with ethylacetate (50 ml). The organic layers were combined, dried over sodiumsulfate, filtered and concentrated in vacuo to give 8.7 g of impureproduct. This residue was purified by column chromatography on Mercksilica gel-60 (5×27 cm) eluting with hexane:ethyl acetate (5:1).Fractions containing the product were combined and concentrated to give6.71 g of desired product.

Alternative preparation of (trans)-2,3-bis[(benzoyloxy)methyl]cyclobutanone

To a solution of [trans)-3,3-diethoxy-1,2-cyclobutanedimethanol,dibenzoate ester (50 g, 0.12 mol) in 1.5 L of acetonitrile was added 570ml of 0.5M sulfuric acid in water. The reaction was stirred under argonfor 16 hours at 25° C., then was diluted with 5 L of ethyl acetate. Themixture was washed with 2×1 L of water, 2×1 L of saturated sodiumbicarbonate, 2×1 L of water and finally 1 L of brine. The organic phasewas dried over sodium sulfate and concentrated to an oil. Triturationwith hexane gave 34 g of crude product. Trituration of this crude solidwith 300 ml of diethyl ether gave 10 g of desired product, mp 76°-78° C.Chilling the filtrate at -30° C. for 4 hours gave 12 g of a second crop,mp 76-78° C., of equal purity.

(F). (1α,2β,3β )-3-Hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoateester and (1α,2β,3α)3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoateester.

To a solution of (trans)-2,3-bis[(benzoyloxy) methyl]cyclobutanone (2.46g, 7.28 mmol) in dry methanol (40 ml) was added sodium cyanoborohydride(1.01 g, 16 mmol). Bromocresol green (3 mg) was added as a pH indicator.When the indicator turned blue, 1N HCl in methanol was added until thecolor turned yellow. After 5 hours, the color no longer changed, and thestarting material was consumed. The solvent was removed in vacuo, andthe residue was dissolved in ethyl acetate (100 ml) and washed withsaturated sodium chloride (50 ml). The aqueous layer was back extractedwith ethyl acetate (50 ml). The organic layers were combined, dried oversodium sulfate, filtered and concentrated in vacuo. The residue waspurified by column chromatography on Merck silica gel-60 (5×55 cm).

Elution with hexane: ethyl acetate (7:3) gave 521 mg of(1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate ester.

Elution with hexane: ethyl acetate (6:3) gave 1.78 g of(1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethano1,1,2-dibenzoate ester.

Alternative preparation of(1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethano1,1,2-dibenzoate ester and(1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethanol,1,2-dibenzoate ester.

To a stirred solution of(trans)-2,3-bis[(benzoyloxy)methyl]cyclobutanone (12.0 g, 0.0355 mol) indry tetrahydrofuran at -78° under nitrogen was added 35.5 ml (0.0355mol) of 1M lithium trisec-butylborohydride in tetrahydrofuran over 3minutes. The reaction was warmed to room temperature, and then saturatedaqueous sodium bicarbonate (34 ml) was added followed by dropwiseaddition of 30% hydrogen peroxide (13.0 ml, 0.127 mol) while keeping thereaction temperature at 30° using an ice water bath. The reaction waswarmed to room temperature, stirred for 30 minutes, and diluted withethyl acetate (400 ml) and water (120 ml). The layers were separated,and the organic layer was extracted with water (100 ml). An emulsionformed, and solid sodium chloride was added to separate the layers. Thetwo water layers were combined and extracted with ethyl acetate. Allethyl acetate layers were combined, dried over sodium sulfate, filteredand concentrated in vacuo to a residue (12.5 g). A portion of thisresidue (7 g) was purified by preparative high pressure liquidchromatography on two Waters Prep Pak 500 silica gel cartridges elutingwith 30% ethyl acetate in hexane at 250 ml/min.(1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate estereluted at 14-22- minutes, and(1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate estereluted at 23-34 minutes. Similar chromatography of the remainder of theabove 12.5 g residue (in two runs, one using 25% ethyl acetate in hexaneand the other using 35% ethyl acetate in hexane) provided a total of8.80 g of (1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoateester and 2.6 g of (1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethanol,dibenzoate ester.

Alternative preparation of (1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethano1,1,2-dibenzoate ester.

To a solution of (trans)-2,3-bis-[(benzoyloxy)methyl]cyclobutanone(13.15 g, 0.0389 mol) in tetrahydrofuran (180 ml) at -78° under nitrogenwas added over 5 minutes 38.9 ml (0.0389 mol) of 1M lithiumtrisiamylborohydride in tetrahydrofuran. The reaction was stirred for 10minutes and then warmed to room temperature. Saturated sodiumbicarbonate solution (36.9 ml) was added followed by 30% hydrogenperoxide (14.19 ml, 0.138 mol) which was added slowly while maintainingthe temperature at 30° using an ice bath. The reaction was diluted withwater (120 ml) and extracted with ethyl acetate (400 ml). The organiclayer was washed with water (100 ml), dried over sodium sulfate, andconcentrated in vacuo to give 17.8 g of the crude desired product as aresidue containing no detectable(1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate ester.The residue was purified by preparative high pressure liquidchromatography on two Waters Prep 500 silica gel columns eluting with30% ethyl acetate in hexane to give 9.17 g of(1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate ester.

Alternatively the crude product (42 g) obtained from the reduction of40.5 g (0.12 mol) of (trans)-2,3-bis-[(benzoyloxy)methyl]cyclobutanonewith 120 ml (0.12 mol) of 1 M lithium trisiamylborohydride (as above)was dissolved in 100 ml of hexane/ethyl acetate (2/1) and applied to adry pad of 1.2 L of Merck silica gel-60. The pad was washed with 5 L ofthe same solvent mixture, taking 500 ml fractions. The productcontaining fractions were combined and evaporated to give 39.8 g of thedesired material as a colorless liquid, pure enough for use in the nextstep of the synthesis.

(G)(1α,2β,3β)-3-[[(4-Methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester.

To a solution of (1α,2β,3β)-3-hydroxy-1, 2-cyclobutanedimethanol,1,2-dibenzoate ester (7.31 g, 0.0215 mol), previously dried byconcentrating it from dry pyridine (2×20 ml), in 36 ml of dry pyridinewas added p-toluenesulfonyl chloride (6.56 g, 0.0344 mol). The reactionwas stirred for 16 hours at 60° under nitrogen, and the pyridine wasremoved in vacuo. Residual pyridine was removed by co-distillation withtoluene (2×30 ml). The residue was dissolved in ethyl acetate (480 ml)and washed with saturated potassium carbonate. The organic layer wasdried over sodium sulfate, filtered and concentrated in vacuo to aresidue which was purified by chromatography on Merck silical gel-60(1500 ml). The column was eluted with a forerun of 3000 ml of ethylacetate:hexane (1:5). The column was then eluted with ethylacetate:hexane (1:3) collecting 50 ml fractions. The appropriatefractions were combined and concentrated to give 7.00 g of(1α,2β,3β)-3[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester.

Alternatively, after heating(1α,2β,3β)-3-hydroxy-1,2-cyclobutanedimethanol, 1,2-dibenzoate ester(39.8 g, 117 mmol) with p-toluenesulfonyl chloride (24.65 g, 128.5 mmol)in 60 ml of pyridine at 60° C. for 22 hours, the temperature was loweredto 40° C. and 2 ml of water was added. After 2 hours, the volatiles wereremoved and the residue was partitioned between ethyl acetate and water.The organic layer was washed with 3% sodium bicarbonate and dried oversodium sulfate. The crude material obtained on concentration of thesolvent was triturated with pentane to give 39.4 g of crude product.This material was dissolved in 120 ml of ethyl acetate with gentlewarming. The solution was cooled to room temperature and diluted with120 ml of pentane. Standing for several hours at +5° C. gave crystalswhich were filtered and dried to give 32.6 g of the pure desiredproduct.

Alternate preparation of (1α,2β,3β)-3-[[(4-Methylphenyl)sulfonyl]-oxy]-1,2-cyclobutanedimethanol,dibenzoate ester.

To a solution of (1α,2β,3α)-3-hydroxy-1,2-cyclobutanedimethanol,dibenzoate ester (3.096 g, 9.10 mmol) in dry toluene (25 ml) was addedp-toluenesulfonic acid monohydrate (2.08 g, 10.9 mmol), triethylamine(1.51 ml, 10.9 mmol), triphenylphosphine (3.81 g, 14.6 mmol) anddiisopropyl azodicarboxylate (2.87 ml, 14.6 mmol). The reaction washeated at 80° under nitrogen. Additional triphenylphosphine (1.90 g, 7.3mmol) and diisopropyl azodicarboxylate (1.43 ml, 7.3 mmol) were addedafter 1 hour and again after 3 hours. After another 3 hours of heating,additional triphenylphosphine (0.95 g, 3.65 mmol) and diisopropylazodicarboxylate (0.717 ml, 3.65 mmol) were added. The reaction washeated for an additional hour, cooled to room temperature and filtered.The precipitate was washed with toluene (20 ml), and the filtrate andwash were combined and concentrated in vacuo to a residue which wasdissolved in ethyl acetate (100 ml). The ethyl acetate solution waswashed with water (2×30 ml), dried over sodium sulfate, filtered andconcentrated in vacuo. The residue was purified by chromatography onMerck silica gel-60 (300 ml) using hexane:ethyl acetate (5:1), and theappropriate fractions were combined and concentrated to 20 ml. Thisconcentrate was diluted with 30 ml of hexane and allowed to stand atroom temperature overnight. The crystals were collected by filtration,washed with hexane and dried to give 2.18 g (batch 1) of pure desiredproduct.

The mother liquors from batch 1 were concentrated to 40 ml and left atroom temperature overnight. The crystals (batch 2) were collected byfiltration, dried in vacuo, and chromatographed on Merck silica gel-60(300 ml) using 2% ethyl acetate in toluene to give 1.02 g (batch 3) ofstill impure desired product. The mother liquors from batch 2 werechromatographed on Merck silica gel-60 (300 ml) using 2% ethyl acetatein toluene to give 187 mg (batch 4) of still impure desired product.Batches 3 and 4 were combined, and recrystallized from hexane:ethylacetate to give an additional 770 mg of pure desired product. The totalyield of pure desired product was 2.95 g.

(H)(1α,2β,3α)-3-[2-Amino-6-(phenylmethoxy)9H-purin-9-yl]-1,2-cyclobutanedimethanol,1,2-dibenzoate ester.

To a solution of(1α,2β,3β)-3-[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate (1.072 g, 2.17 mmol) in dimethylformamide (20 ml) was added2-amino-6-(phenylmethoxy)9H-purine (784 mg, 3.25 mmol), 18-crown-6 (573mg, 2.17 mmol) and potassium carbonate (600 mg, 4.34 mmol). The reactionwas stirred under nitrogen at 110° for 24 hours. The solvents wereremoved in vacuo, and the residue was chromatographed on column of Mercksilica gel-60 (2.5×20 cm) using ethyl acetate:hexane (3:1) to give 400mg of pure desired product. Other fractions that contained impuredesired product were combined and rechromatographed on Merck silicagel-60 (1.5×30 cm) using ethyl acetate hexane (2:1) to give 52 mg ofadditional desired product, yielding a total of 452 mg of desiredproduct.

(I)(1α,2β,3α)-3-[2-Amino-6-(phenylmethoxy)-9H-purin-9-yl]-1,2-cyclobutanedimethanol

To a solution of(6α,2β,3α)-3-[2-amino-6-(phenylmethoxy)-9H-purin-9-yl]-1,2-cyclobutanedimethanol,1,2-dibenzoate ester (452 mg, 0.803 mmol) in dry methanol (12 ml) wasadded a 25% solution of sodium methoxide in methanol (109 μl 0.482mmol). The reaction was stirred under nitrogen at 40° for 1 hour. Thesolvent was removed in vacuo and water (10 ml) was added. The pH waslowered to 7 with 1N HCl. The solvents were removed in vacuo and theresidue was triturated with ether (2×20 ml) and dried to give 358 mg ofcrude desired product, which was then used in the next step.

(J) (1α,2β,3α)-9-[2,3-Bis(hydroxymethyl)cyclobutyl]guanine

To a suspension of(1α,2β,3α)-3-[2-amino-6-(phenylmethoxy)-9H-purin-9-yl]-1,2-cyclobutanedimethanol(358 mg, 1.0 mmol) in methanol (5 ml) was added 3N HCl (2.5 ml). Thereaction was stirred for 4 hours at 45° . The solvents were removed invacuo, and the residue was dissolved in water (20 ml). The pH was raisedto 7 with 1N KOH. A 10% aliquot was taken, and the solvents were removedin vacuo. The residue was concentrated from methanol (3×4 ml) and ethylacetate (2×4 ml). The residue was dissolved in water (4 ml) with heatingand applied to a column of CHP-20P resin [1.1×20 cm; Mitsubishi ChemicalIndustries Ltd. (75-150 micron)]. Elution with water, 2%acetonitrile/water, and 4% acetonitrile/water gave 11 mg of desiredproduct.

The remaining 90% of the reaction was concentrated in vacuo and thenconcentrated from methanol (3×20 ml) and ethyl acetate (2×20 ml). Theresidue was dissolved in water (30 ml) with heating and applied to acolumn of CHP-20P resin (2.5×15 cm). Elution with water, 2%acetonitrile/water, 4% acetonitrile/water and 10% acetonitrile/watergave 111 mg of additional(1α,2β,3α)-9-[2,3-bis(hydroxymethyl)cyclobutyl]guanine having m.p.>220°.

Calculated for C₁₁ H₁₅ N₅ O₃.1.43 H₂ O: C, 45.40; H, 6.18; N, 24.08; H₂O, 8.83. Found:C, 45.66; H, 5.95; N, 23.82, H₂ O, 8.83.

EXAMPLE 2 (1α,2β,3α)-3-(6-Amino-9H-purin-9-yl)1,2-cyclobutanedimethanol(A) (1α,2β,3α)-3-(6-Amino-9H-purin-9-yl)-1,2-cyclobutanedimethanol,dibenzoate ester.

To a solution of(1α,2β,3β)-3-[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester (988 mg, 2 mmol) in dry dimethylformamide (20 ml) undernitrogen was added adenine (405 mg, 3 mmol), 18-crown-6 (538 mg, 2mmol), and potassium carbonate (276 mg, 2 mmol). The reaction was heatedat 110° for 16 hours, and then the solvent was removed in vacuo to givea residue, which was purified by column chromatography on Merck silicagel-60 (400 ml). Elution with 0.1%, 0.5%, 5% and 10% methanol in ethylacetate gave 522 mg of still impure product. Column chromatography ofthis material on Merck silica gel-60 (400 ml) usingdichloromethane-methanol (20:1) afforded 400 mg of pure(1α,2β,3α)-3-(6-amino-9H-purin-9-yl)-1,2cyclobutanedimethanol,dibenzoate ester.

(B) (1α,2β,3α)-3-(6-Amino-9H-purin-9-yl)-1,2cyclobutanedimethanol

To a suspension of(1α,2β,3α)-3-(6-amino-9H-purin-9-yl)-1,2-cyclobutanedimethanol,dibenzoate ester (400 mg, 0.899 mmol) in dry methanol (20 ml) was addeda 25% solution of sodium methoxide in methanol (123 μl, 0.539 mmol). Themixture was stirred at 40° for 45 minutes, and then the solvent wasremoved in vacuo. The residue was slurried in water (20 ml), the pH wasadjusted to 7.0 using 1N HCl, and the volatiles were removed. Theresidue was purified by column chromatography on CHP-20P resin. Elutionwith water, a gradient of 0 to 20% methanol in water and then 20% and30% methanol in water afforded 128 mg of(1α,2β,3α)-3-(6-amino-9H-purin-9-yl)-1,,2-cyclobutanedimethanol as asolid having m.p. 181-183°.

Calculated for C₁₁ H₁₅ N₅ O₂ 0.1 H₂ O: C,52.63; H,6.10; N,27.90.Found:C,52.64; H.6.10; N,28.00.

EXAMPLE 3(1α,2β,3α)-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedione(A) (1α,2β,3α)-1-[2,3-Bis[(benzoyloxy)methyl]cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedione

A mixture of(1α,2β,3β)-3[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester, (1.245 g, 2.52 mmol), thymine (625 mg, 4.96 mmol),potassium carbonate (1.39 g, 10.1 mmol) and 18-crown-6 (664 mg, 2.51mmol) in dry dimethylformamide (12.5 ml) under argon was heated withstirring at 105° for 16 hours and then at 125° for 1 hour. Additionalthymine (310 mg, 2.2 mmol) and potassium carbonate (354 mg, 2.6 mmol)were added, and heating at 125° was continued for 2 hours. The reactionmixture was cooled and filtered, and the insolubles were washed withdimethylformamide. The dimethylformamide filtrates were combined andevaporated to a residue, which was triturated with ethyl acetate. Thesolids were removed by filtration, and the filtrate was evaporated to aresidue. This residue was dissolved in a small volume of ethylacetatehexane (ca. 1:1) and applied to a column of Merck silica gel-60(5×11.5 cm) packed in hexane. Elution with ethyl acetate-hexane (4:1)and then ethyl acetate gave 219 mg of partially purified desiredproduct. Chromatography of this material on a column of Merck silicagel-60 (packed in dichloromethane) by elution with 10%, 20%, 30% and 50%ethyl acetate in dichloromethane afforded 166 mg of pure(1α,2β,3α)-1-[2,2-bis[benzoyloxy)methyl]cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedioneas a white solid.

(B)(1α,2β,3α)-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedione.

A 25% solution of sodium methoxide in methanol (44.7 μl, 0.196 mmol) wasadded to a stirred suspension of(1α,2β,3α)-1-[2,3-bis[(benzoyloxy)methyl]cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedione(146 mg, 0.326 mmol) in dry methanol (4.9 ml) under argon at 40°. After4 hours, the clear solution was cooled to room temperature andconcentrated in vacuo to a residue, which was taken up in water. The pHwas adjusted to 7 using dilute hydrochloric acid, and the solution wasapplied to a column (1.5×21 cm) of CHP-20P resin packed in water.Elution with water, 2%, 4% and 10% acetonitrile in water afforded, afterevaporation and subsequent lyophilization from water, 58 mg of(1α,2β,3α)-1-[2,3bis(hydroxymethyl)cyclobutyl]-5-methyl-2,4(1H,3H)-pyrimidinedioneas a deliquescent solid. Proton NMR (270 MHz, ##STR73##tetramethylsilane) δ: 11.11 (broad singlet, 1H), 7.64 (doublet, J=1.1Hz, 1H), 4.56 (multiplet, 2H), 4.47 (multiplet, 2H), 4.47 (multiplet,1H), 3.44 (multiplet, 4H), 2.5 (multiplet, ##STR74## solvent+1H), 1.85(multiplet, 1H), 1.84 (multiplet, 1H), 1.79 (doublet, J=1.1 Hz, 3H).

EXAMPLE 4(1α,2β,3α)-4-Amino-1-[2,3-bis(hydroxymethyl)cyclobutyl]-2(1H)-pyrimidinone(A)(1α,2β,3α)-4-Amino-1-[2,3-bis[(benzoyloxy)methyl)cyclobutyl]-2(1H)-pyrimidinone

A mixture of(1α,2β,3β)-3-[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester (1.51 g, 3.05 mmol), cytosine (678 mg, 6.10 mmol),potassium carbonate (1.69 g, 12.2 mmol) and 18-crown-6 (804 mg, 3.04mmol) in 12.5 ml of dry dimethyl sulfoxide was stirred under argon at112° for 4.5 hours. The reaction mixture was cooled to room temperatureand neutralized by the addition of glacial acetic acid (0.7 ml, 12.2mmol). Solvent was removed in vacuo, and the residue was taken up inethyl acetate. Solid material was removed by filtration, and the filtercake was washed with ethyl acetate. The ethyl acetate filtrate wasconcentrated to a residue, which was dissolved in toluene and applied toa column of Merck silica gel (2.5×28.5 cm) packed in toluene. Elutionwith isopropanol in toluene afforded 156 mg of the desired product.

(B) (1α,2β,3α)-4-Amino-1-[2,3-bis(hydroxymethyl)cyclobutyl]-2(1H)-pyrimidinone.

A 25% solution of sodium methoxide in methanol (48 μl, 0.209 mmol) wasadded to a solution of(1α,2β,3α)-4-amino-1-[2,3-bis[(benzoyloxy)methyl]cyclobutyl]-2(1H)-pyrimidinone(151.3 mg, 0.349 mmol) in 5.25 ml of dry methanol. The reaction wasstirred at 40° for 75 minutes and cooled to room temperature. Thesolvent was removed in vacuo, and the residue was dissolved in water.The pH was adjusted to 7.05 with 1N HCl. The aqueous solution was loadedonto a column of CHP-20P resin packed in water, and the column wasflushed with 50 ml of water and then eluted with a continuous gradientof 0-50% acetonitrile in water. Combination of the appropriate fractionsand removal of solvent in vacuo afforded the desired product as atransparent glass (52 mg). Proton NMR (270 MHz, ##STR75##tetramethylsilane) δ: 7.69 (doublet. J=7Hz, 1H), 6.98 (broad singlet,2H), 5.71 (doublet, J=7.6Hz, 1H), 4.65 (broad multiplet, 2H), 4.37(multiplet, 1H), 3.43 (multiplet, 4H), 2.43 (multiplet, 1H), 2.31(mulitiplet, 1H), 2.20 (multiplet, 1H), 1.77 (multiplet, 1H).

EXAMPLE 5[1α(E),2β,3α]-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-5-(2-bromoethenyl)-2,4(1H,3H)pyrimidinedione(A)(1α,2β,3α)-1-[2,3-Bis[(benzoyloxy)methyl]cyclobutyl]-2,4(1H,3H)-pyrimidinedione.

To a solution of uracil (1.26 g, 11.23 mmol, dried at 50° for 16 hours)and 18-crown-6 (1.98 g, 7.49 mmol) in dimethylsulfoxide (9 ml) at 50°was added potassium carbonate (2.07 g, 14.98 mmol) and(1α,2β,3β)-3-[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester (3.7 g, 7.49 mmol). Upon heating to 100° undernitrogen, an emulsion formed. Additional dimethylsulfoxide (3 ml) wasadded, and the reaction was stirred at 100° for 24 hours. The solventswere removed in vacuo to give a residue, which was purified bychromatography on Merck silica gel-60 (700 ml) using a gradient oftoluene to 3% isopropyl alcohol in toluene. The appropriate fractionswere combined to give 850 mg of pure desired product. Fractionscontaining impure desired product were combined and concentrated to aresidue, which was dissolved in toluene (1 ml). The crystals that formedwere collected and dried to give 35 mg of additional pure desiredproduct.

(B)(1α,2β,3α)-1-[2,3-Bis[hydroxymethyl)cyclobutyl]-2,4(1H,3H)-pyrimidinedione.

To a suspension of (1α,2β,3α)-1-[2,3-bis[(benzoyloxy)methyl]cyclobutyl]-2,4(1H,3H)pyrimidinedione (885 mg, 2.04mmol) in dry methanol (25 ml) was added a 25% solution of sodiummethoxide in methanol (264 μl, 1.22 mmol). The reaction was heated to40° for 3 hours under nitrogen. The solvents were removed in vacuo, andthe residue was dissolved in water (5 ml). The pH was lowered to 7 with1N HCl, and the solution was stored overnight at 0°. The resultingprecipitate and supernatant were purified on a single CHP-20P resincolumn (200 ml) using a step gradient of water, 2% acetonitrile/waterand 4% acetonitrile/water, to give 423 mg of desired product.

(C)(1α,2β,3α)-1-[2,3-Bis[hydroxymethyl)cyclobutyl]-5-iodo-2,4(1H,3H)-pyrimidinedione

To a suspension of(1α,2β,3α)-1-[2,3-bis(hydroxymethyl)cyclobutyl-2,4(1H,3H)-pyrimidinedione(423 mg, 1.87 mmol) in dioxane (38 ml, purified on basic alumina) wasadded iodine (950 mg, 3.74 mmol) and 0.8M nitric acid (2.5 ml, 2 mmol).This solution was stirred at 95° for 90 minutes and cooled to roomtemperature. A solution of saturated aqueous sodium thiosulfate wasadded until the dark red color faded. The reaction was concentrated invacuo to give a slightly yellow residue. This material was purified bychromatography on CHP-20P resin (150 ml) using a gradient of water to50% acetonitrile in water to give 557 mg of desired product.

(D)[1α(E),2β,3α]-3-[1-[2,3-Bis(hydroxymethyl)cyclobutyl]-1,2,3,4-tetrahydro-2,4-dioxo-5-pyrimidinyl]-2-propenoicacid, methyl ester

A suspension of palladium(II)acetate (17.5 mg, 0.078 mmol),triphenylphosphine (40.9 mg, 0.15 mmol) and triethylamine (290 μl, 2.08mmol) in dioxane (20 ml, purified on basic alumina) was heated for 15minutes at 85° under nitrogen, and then a solution of(1α,2β,3α)-1-[2,3-bis(hydroxymethyl)cyclobutyl]-5-iodo-2,4(1H,3H)-pyrimidinedione(457 mg, 1.3 mmol) and methyl acrylate (468 μl, 5.2 mmol) in dioxane (10ml) was added. The reaction was heated at 85° under nitrogen. After 4hours, additional methyl acrylate (234 μl, 2.7 mmol) was added. Afterheating for an additional 2 hours, the reaction was still not complete.Celite (300 mg) was added, and the warm reaction was filtered. Thesolvents were removed in vacuo. The residue was dried by concentratingit from dry dioxane (2×10 ml) and the residue was then submitted to thefollowing reaction conditions.

The reaction was repeated, but this time the oxygen was removed from thedioxane by bubbling argon through the solvent. After heating asuspension of palladium(II) acetate (17.5 mg, 0.078 mmol),triphenylphosphine (40.9 mg, 0.15 mmol), and triethylamine (290 μl, 2.08mmol) in dioxane (20 ml) for 15 minutes at 85° under nitrogen, asolution of the above residue and methyl acrylate (468 μl, 5.2 mmol) indioxane (10 ml) was added. The reaction was heated for 3 hours at 85°.Celite (300 mg) was added and the warm reaction was filtered, cooled toroom temperature, and concentrated in vacuo. The residue was applied toa column of Merck silica gel-60 (150 ml, packed in chloroform) andpurified using a step gradient from chloroform to 5%, 7.5% and 10%methanol/chloroform. The appropriate fractions were combined andconcentrated to give 310 mg of desired product contaminated withtriethylammonium salts. This mixture was dissolved in water (5 ml) andethyl acetate (50 ml). The layers were separated and the water layer wasextracted with ethyl acetate (4×30 ml). The ethyl acetate layers werecombined, dried over sodium sulfate, filtered and concentrated to give230 mg of the desired product.

(E)[6α(E),2β,3α]-3-[1-[2,3-Bis(hydroxymethyl)cyclobutyl]-1,2,3,4-tetrahydro-2,4-dioxo-5-pyrimidinyl]-2-propenoicacid

A solution of[1α(E),2β,3α]-3-[1-[2,3-bis(hydroxymethyl)cyclobutyl]-1,2,3,4-tetrahydro-2,4-dioxo-5-pyrimidinyl]-2-propenoicacid, methyl ester (230 mg, 0.742 mmol) in 2M sodium hydroxide (3.7 ml,7.42 mmol) was stirred at room temperature for 1.5 hours, and thereaction was cooled to 4°. The pH was lowered to 2 with 6N HCl, and thereaction was allowed to stand for 1 hour at 4°. The precipitate wascollected by filtration, washed with water and dried over P₂ O₅ in vacuofor 16 hours to give 120 mg of desired product. The mother liquors andwash were concentrated to 3 ml and allowed to stand at 4° for 16 hours.The crystals were collected, washed with water, dried over P₂ O₅ invacuo for 4 hours to give 7 mg of additional desired product.

(F)[1α(E),2β,3α]-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-5(2-bromoethenyl)-2,4(1H,3H)-pyrimidinedione

To a solution of[1α(E),2β,3α]-3-[1-[2,3-bis(hydroxymethyl)cyclobutyl]-1,2,3,4-tetrahydro-2,4-dioxo-5-pyrimidinyl]-2-propenoicacid (127 mg, 0.429 mmol, dried by evaporation of dimethylformamide, 2×3ml) in dimethylformamide (2 ml) was added potassium bicarbonate (129 mg,1.29 mmol). A solution of N-bromosuccinimide (76 mg, 0.429 mmol) indimethylformamide (1 ml) was added, and the reaction was stirred at roomtemperature for 2.5 hours. The reaction was filtered and concentrated invacuo. The residue was concentrated from water (2×5 ml), and thenchromatographed on CHP 20P resin (110 ml) using a gradient of water to30% acetonitrile in water to give, after concentration in vacuo, 99 mgof[1α(E),2β,3α]-1-[2,3-bis(hydroxymethyl)cyclobutyl]-5(2-bromoethenyl)-2,4-(1H,3H)-pyrimidinedionehaving m.p. 155-157°.

Calculated for C₁₂ H₁₅ N₂ O₄ Br.0.31 H₂ O. C, 42.79; H,4.68; N,8.32.Found: C, 42.85; H,4.69; N,8.26.

EXAMPLE 6(1α,2β,3α)-2-Amino-9-[2,3-bis(hydroxymethyl)cyclobutyl]-8-bromo-1,9,dihydro-6H-purin-6-one

To a stirred suspension of(1α,2β,3α)-9-[2,3-bis(hydroxymethyl)cyclobutylguanine (72 mg, 0.272mmol) in water (9 ml) was added 0.5 ml of a saturated bromine-watersolution. Additional bromine-water solution (0.5 ml) was added after 25minutes and again after 50 minutes. After 15 minutes of additionalstirring, the precipitated material was filtered, washed with water,slurried in water (3 ml), and applied to a CHP-20P column (24 ml) packedin water. Elution with a step gradient of water, 4% acetonitrile/water,and 8% acetonitrile/water gave 45 mg of desired product. This materialwas combined with 49 mg of desired product from a similar reaction runon the same scale, and the combined products were crystallized fromwater (7 ml) to give 74 mg of(1α,2β,3α)-2-amino-9-[2,3-bis(hydroxymethyl)cyclobutyl]-8-bromo-1,9,dihydro-6H-purin-6-onehaving m.p. 130°. NMR (270 MHz, ##STR76## tetramethylsilane)δ: 10.67broad singlet, 1H), 6.43 (broad singlet, 2U), 4.59 (quartet, J=9Hz,1H),4.55 (triplet, J=5Hz,1H), 4.48 (triplet, J=5Hz, 1H), 3.59 (triplet,J=6Hz, 2H), 3.44 (triplet, J=5Hz, 2H), 2.56 (multiplet, 2H), 2.26(multiplet, 1H), 2.21 (multiplet, 1H).

EXAMPLE 7(1α,2β,3α)-1-[2,3-Bis(hydroxymethyl)cyclobutyl.-5-iodo-2,4(1H,3H)-pyrimidinedione(A)(1α,2β,3α)-1-[2,3-Bis(benzoyloxy)methyl]cyclobutyl]-2,4(1H,3H)-pyrimidinedione

A mixture of(1α,2β,3β)-3-[[(4-methylphenyl)sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester (1.25 g, 5.07 mmol), uracil (0.567 g, 5.07 mmol),potassium carbonate (1.40 g, 10.2 mmol) and 18-crown-6 (670 mg, 2.54mmol) in dry DMSO (12.5 ml) was heated at 110° for 4.5 hours. Thesolvent was removed in vacuo and the resulting semi-solid was trituratedtwice with ethyl acetate. The combined ethyl acetate supernatants wereconcentrated to a small volume, diluted with an equal volume of hexaneand applied to a column of Merck silica gel-60 (2.5×25 cm) packed inhexane. The column was eluted with ethyl acetate-hexane (1:4) and (1:1)and then ethyl acetate to afford partially purified desired product (250mg). Chromatography of this material on a silical gel column (1.5×24.5cm) packed in methylene chloride, eluting with ethyl acetatemethylenechloride (1:4) and (1:1) and then ethyl acetate failed to resolve theimpurities. Subsequent chromatography on a silica gel column (1.5×25 cm)packed in toluene and eluting with isopropanol-toluene (4:96) affordedthe pure desired product (56.5 mg) as well as impure desired product.Recrystallizaiton of the impure material from toluene affordedadditional pure desired product (86.3 mg; giving a total yield of 143mg).

(B)(1α,2β,3α)-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-2,4(1H,3H)-pyrimidinedione

A mixture of(1α,2β,3α)-1-[2,3-bis(benzoyloxy)methyl]cyclobutyl]-2,4(1H,3H)-pyrimidinedione(142.9 mg, 0.329 mmol), 45 μl of a 25% solution of sodium methoxide inmethanol, and 4.9 ml of dry methanol was stirred at 40° under argon for8.5 hours. The reaction was cooled to room temperature, and the solventwas removed in vacuo. The sticky residue was partially dissolved in afew milliliters of water and the pH was adjusted to 7.00 with dilutehydrochloric acid and sodium bicarbonate. This solution (7-8 ml) wasapplied to a column of CHP-20P resin (1.5×23.5 cm) packed in water.After elution with water (ca. 50 ml), the column was eluted with aqueousacetonitrile (2%, 4% and 10%) to give 55.8 mg of desired product as awhite solid.

(C)(1α,2β,3α)-1-[2,3-Bis(hydroxymethyl)cyclobutyl]-5-iodo-2,4(1H,3H)-pyrimidinedione

A solution of(1α,2β,3α)-1-[2,3-bis(hydroxymethyl)cyclobutyl]-2,4(1H,3H)-pyrimidinedione(54.7 mg, 0.242 mmol), iodine (123 mg, 0.484 mmol), and aqueous nitricacid (0.8N, 0.256 mmol) in 5 ml of dioxane was stirred at 105° for 85minutes. After cooling to room temperature, the mixture was decolorizedwith aqueous sodium thiosulfate and concentrated in vacuo to a solid.The solid was taken up in water and concentrated in vacuo (3 times). Theresultant solid was partially dissolved in water and applied to a columnof CHP-20P resin (1.5×20 cm) packed in water. After elution with water(ca. 50 ml), the column was eluted with a continuous gradient from waterto 50% acetonitrile in water to give 67.3 mg of(1α,2β,3α)-1-[2,3-bis(hydroxymethyl)cyclobutyl]5-iodo-2,4(1H,3H)-pyrimidinedioneas a white solid having m.p. 17014 171°.

Calculated for C₁₀ H₁₃ IN₂ O₄.0.27 H₂ O: C, 33.65; H,3.82; N,7.85.Found: C, 33.68; H,3.77; N,7.82.

EXAMPLE 8(1α,2β,3α)-5-Amino-3-[2,3-bis(hydroxymethyl)cyclobutyl]-3,6-dihydro-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-one(A) 4-Chlorobenzenediazonium chloride

To a suspension of 4-chloroaniline (21.14 g, 0.166 mol) in water (156ml) and 12N HCl (46 ml) at 0° was added sodium nitrite (12.62 g, 0.182mol) in water (156 ml) over 20 minutes keeping the reaction temperaturebelow 10°. The solution of 4-chlorobenzenediazonium chloride wasfiltered, kept at 0° for 30 minutes and then used in the next step.

(B) 6-Chloro-5-[(4-chlorophenyl)azo-2,4-pyrimidinediamine

To a suspension of 4-chloro-2,6-diaminopyrimidine (21.68 g, 0.150 mol)in water (750 ml) and acetic acid (750 ml) was added sodium acetate (300g). Solution occurred after stirring for 20 minutes, and then thesolution of 4-chlorobenzenediazonium chloride (0.166 mol) was added withcooling over 30 minutes at a rate that kept the reaction at 18°. Thereacton was stirred overnight at room temperature, and the orangecrystals were filtered, washed with water (4×400 ml), and dried in vacuoto give 17.6 g of6-chloro-5-[(4-chlorophenyl)azo]-2,4-pyrimidinediamine. The motherliquors were cooled to 5° for 20 hours, and the crystals were collectedand dried in vacuo to give 6.94 g of additional6-chloro-5-[(4-chlorophenyl)azo]-2,4-pyrimidineadiamine.

(C) 6-Chloro-2,4,5-pyrimidinetriamine

A suspension of 6-chloro-5-[(4-chlorophenyl)azo]-2,4-pyrimidinediamine(24.55 g, 0.0906 mol) in ethanol (640 ml), water (640 ml) and aceticacid (64 ml) was heated to 70° under nitrogen. Zinc dust (75 g) wasadded slowly over 1 hour, and then the reaction was stirred anadditional hour at 70°. Then the reaction was cooled to room temperatureand filtered under nitrogen. The filtrate was cooled to 0° and the pHwas raised to 10 with 10% sodium hydroxide (400 ml). The precipitatedzinc hydroxide was removed by filtration through Celite, and the darkred filtrate was neutralized to pH 7 with glacial acetic acid andconcentrated to 300 ml. Water (50 ml) was added, the reaction was cooledto 0°, and the pH raised to 9 with 10% NaOH. The solution was allowed tostand at 5° for 3 days. The crystals were collected, washed with water(50 ml) and then ether (50 ml), and dried at 35° for 16 hours in vacuoto give 10.94 g of desired product.

(D) 7-Chloro-1H-1,2,3-triazolo[4,5-d]pyrimidin-5-amine

A solution of 6-chloro-2,4,5-pyrimidinetriamine (10.94 g, 0.0686 mol)and isoamyl nitrite (9.20 ml, 0.0686 mol)in dioxane (500 ml, freshlypurified by passage through basic alumina) was heated under nitrogenwith stirring for 2 hours at 90°. The reaction mixture was cooled,treated with activated carbon, filtered, and concentrated to 150 ml.Petroleum ether (250 ml, bp 35-60° ) was added. The precipitate wasfiltered, washed the petroleum ether (50 ml) and dried in vacuo over P₂O₅ at 40° for 16 hours to give 9.23 g of crude desired product which wasthen used in the next step.

(E) 7-(Phenylmethoxy)-1H-1,2,3-triazolo[4,5-d]pyrimidin-5-amine

Sodium metal (3.7 g, 0.162 mol) was added in pieces to benzyl alcohol(117 ml, 1.13 mol) under nitrogen over 20 minutes. The reaction was thenheated to 80° for 90 minutes. All of the sodium metal dissolved, and thereaction was left at room temperature for 16 hours.7-Chloro-1H-1,2,3triazolo[4,5-d]pyrimidin-5-amine (9.23 g. 0.0541 mol)was then added, and the reaction was heated to 60° for 5 hours. Thereaction was cooled and left at 5° for 16 hours. Water (500 ml) wasadded to dissolve the precipitate and then the mixture was extractedwith ether (3×200 ml). The pH of the water layer was lowered to 7.0 withconcentrated HCl and then to 5.5 with 1N HCl. The precipitate wasfiltered and dried at room temperature over P₂ O₅ in vacuo to give 8.05g of desired product.

(F)(1α,2β,3α)-3-[5-Amino-7-(phenylmethoxy)3H-1,2,3-triazolo[4,5-d]-pyrimidin-3-yl]1,2-cyclobutanedimethanol,dibenzoate ester

To a suspension of 60% NaH (78 mg, 1.96 mmol) in dimethylformamide (4ml) under nitrogen was added 7-(phenymethoxy)-1H-1,2,3-triazolo[4.5-d]pyrimidin-5-amine (474 mg, 1.96 mmol). After 10 minutes,(1α,2β,3β)-3-[[(4-methylphenyl) sulfonyl]oxy]-1,2-cyclobutanedimethanol,dibenzoate ester (880 mg, 1.78 mmol) was added, and the reaction washeated at 85° for 24 hours. The solvents were removed in vacuo and theresidue was triturated with ethyl acetate (3×30 ml) and filtered. Theethyl acetate extracts were combined and concentrated to a residue,which was purified on Merck silica gel-60 (100 ml), eluting with astepwise gradient of 10% ethyl acetate in hexane to 100% ethyl acetate.The desired product eluted with 50% ethyl acetate in hexane to afford205 mg of (1α,2β,3α)-3-[5-amino-7-(phenylmethoxy)-3H-1,2,3-triazolo[4,5-d]-pyrimidin-3-yl]-1,2-cyclobutanedimethanol, dibenzoate ester.

(G)(1α,2β,3α)-3-[5-Amino-7-(phenylmethoxy)3H-1,2,3-triazolo[4,5-d-pyrimidin-3-yl]1,2-cyclobutanedimethanol

To a solution of(1α,2β,3α)-3-[5-amino-7-(phenylmethoxy)-3H-1,2,3-triazolo[4,5-d]-pyrimidin-3-yl]-1,2-cyclobutanedimethanol,dibenzoate ester (205 mg, 0.363 mmol) in dry methanol (6 ml) was added a25% solution of sodium methoxide in methanol (50 μl, 0.218 mmol). Thiswas heated to 40° under nitrogen for 1 hour, and then water (2 ml) wasadded and the pH was adjusted to 7 with 1M HCl. The reaction wasconcentrated in vacuo to give crude desired product.

(H)(1α,2β,3α)-5-Amino-3-[2,3-bis(hydroxymethyl)cyclobutyl]-3,6-dihydro-7H-1,2,3-triazolo[4,5-d]pyrimidin-7-one.

Crude (1α,2β,3α)-3-[5-amino-7-(phenylmethoxy)-3H-1,2,3-triazolo[4,5-d]-pyrimidin-3-yl]-1,2-cyclobutanedimethanol fromabove was slurried in 1.5 ml of methanol and then 3N HCl (600 μl) wasadded. The reaction was heated to 45° for 4 hours, and left at roomtemperature for 16 hours. The pH was raised to 7 with 1N KOH, and thesolution was concentrated in vacuo to a residue. Chromatography of thisresidue on CHP-20P resin (34 ml) using a gradient of water to 70%acetonitrile in water gave 64 mg of(1α,2β,3α)-5-amino-3-[2,3-bis(hydroxymethyl)cyclobutyl]-3,6-dihydro-7H-1,2,3-triazolo]4,5-d]-pyrimidin-7-onehaving m.p.>200°.

Calculated for C₁₀ H₁₄ N₆ O₃.2.5 H₂ O: C,38.57;H,6.15;N,26.99. Found:C,39.17;H,4.98;N,26.51.

EXAMPLE 9 Treatment of Viral Infection in Cell Culture in Vitro

Assays were performed in cell culture systems to determine theconcentrations of compounds that are effective in preventing severalkinds of viral infections. The assays are described below, and theresults are presented in Table 1.

Abbreviations

HSV-1 (herpes simplex virus type 1, strain Schooler), HSV-2 (herpessimplex virus type 2, strain 186), VZV (varicella zoster virus, strainELLEN), HCMV (human cytomegalovirus, strain AD 169), MuLV (murineleukemia virus, strain CAS), HIV (human immunodeficiency virus, strainHTLV-IIIB).

Cell Culture Assays

HSV-1, HSV-2, HCMV, and VZV antiviral assays: Virus was adsorbed toWI-38 cell culture monolayers in 6 well culture plates (Costar,Cambridge, MA) for 1 hour prior to addition of maintenance mediumcontaining duplicate dilutions of the test compound. Inhibition ofplaque development was evaluated on fixed and stained monolayers after 4days incubation at 37° C. for HSV-1 and HSV-2 and after 6-7 daysincubation at 37° C. for HCMV and VZV. ID₅₀ values were determined fromthe drug concentration which conferred at least a 50% plaque reductioncompared to virus controls.

MuLV antiviral assay: Antiviral assays using MuLV were performed withsome modification, as described by Rowe et al. and Shannon et al.. SC-1cells were planted at approximately 2×10⁵ cell per well in 6 wellplates. After overnight incubation at 37° C., the cell cultures weresensitized with DEAE-Dextran for one hour at 37° C., rinsed andinoculated with MuLV. Cultures were re-fed with growth medium containingdifferent concentrations of the test compound. After three more days at37° C., cultures were re-fed with fresh medium plus test compounds andincubated at 37° C. for an additional 3 days. Cultures were then washedto remove medium, ultraviolet light irradiated, and planted withapproximately 5×10⁵ XC cells per well in cell growth medium containingthe appropriate concentration of the test compound. The cultures werethen incubated for an additional 4 days, with a re-feed using growthmedium containing test compound at the second day following XC celloverlay. Finally the cultures were rinsed, stained and syncytial plaqueswere counted. References:

Rowe, W. P., Pugh, W. E., and Hartley, J. W., (1970), Plaque AssayTechniques for Murine Leukemia Viruses, Viroloqy, 42: 1136-1139.

Shannon, W. M, Brockman, R. W., Westbrook L., Shaddix, S., and Shabel,F. M., (1974) Inhibition of Gross Leukemia Virus-Induced PlaqueFormation in XC Cells by 3-Deazauridine, J. Natl., Cancer Inst.,52:199-205.

HIV antiviral assay: Suspensions of CEM(Nara and Fischinger, Nature,332:469, 1988) cells were infected at a multiplicity of infection (e.g.virus/cell) of 0.12 with HIV (strain HTLV-III B). After adsorption for1-2 hours at 37° C., infected cells were diluted in growth medium (RPMI1640 containing the antibiotics penicillin plus streptomycin and 10%fetal calf serum) to a final cell concentration of 1×10⁴ viablecells/culture well in the presence of serial dilutions of the testcompound, starting at 100 μg/ml. Triplicate samples at each drugconcentration were used. Cultures of uninfected CEM cells were similarlyprepared and incubated with serial dilutions of test compound induplicate. All assays were performed in 96 well disposable cell cultureplates. Untreated (infected and uninfected) cells were included ascontrols. All cultures were incubated for 7 days at 37° C. in ahumidified atmosphere containing 5% CO₂. Following incubation, viablecell numbers were counted in each well using a colorimetric assayfollowing incubation of cells with XTT-PMS solution (XTT tetrazoliumreagent plus phenazine methosulfate PMS).

Percent reduction of viral cytopathic effect (CPE) in drug treatedcompared to untreated virus infected cells, and percent reduction ofcell viability in drug treated uninfected cells compared to untreatedcontrols were calculated and plotted versus the drug concentrationstested. From these plots, the ID₅₀ (the minimum drug concentration thatinhibits CPE by 50%) for each drug was calculated.

                                      TABLE 1                                     __________________________________________________________________________     ##STR77##                                                                                   ID.sub.50 (μM) for the following viruses                    R.sub.1        HSV-1                                                                              HSV-2                                                                              VZV  HCMV MuLV                                                                              HIV                                    __________________________________________________________________________     ##STR78##     0.08-0.2                                                                           0.04-0.08                                                                          0.2  3.8  3.8 30                                      ##STR79##     8.0  4.0-8.0                                                                            0.8-2.0                                                                            0.8  ND* 6.8                                     ##STR80##      6-14                                                                              >284 14-28                                                                              >284 ND  ND                                      ##STR81##     444  444  22   22-44                                                                              ND  ND                                      ##STR82##     7.5  7.5  3.8- 38                                                                            376  ND  ND                                      ##STR83##     10-30                                                                              >302 0.03-0.06                                                                          >302 ND  ND                                     __________________________________________________________________________     *ND = not determined                                                     

What we claim is:
 1. A compound having the formula ##STR84## or apharmaceutically acceptable salt thereof wherein ##STR85##
 2. A compoundin accordance with claim 1,(1α,2β,3α)-5-amino-3-[2,3-bis(hydroxymethyl)cyclobutyl]-3,6-dihydro-7H-1,2,3-triazolo[4,5-d]-pyrimidin-7-one.3. An antiviral composition useful for treating a viral infection in amammalian specie comprising an effective amount of an antiviral agent ofclaim 1 and a pharmaceutically acceptable vehicle.
 4. The method oftreating a viral infection in a mammalian specie comprisingadministering an effective amount of the composition of claim 3.